It is related with a data migration technique, and more particularly, it relates to a data protection technique against illegal modification, in the course of data moving from a storage area in a source to a storage area in a destination.
These days, documentation by a computer, utilization of database, and widespread use of the Internet increase the amount of electronic information. Such electronic information may contain valuable information which is worth to preserve for a long term. In order to preserve this kind of valuable information in a form of electronic data for 10 or 30 years, or semi-permanently, following steps are necessary. That is, as shown in FIG. 14A, by use of computer 91, electronic data stored in storage device 92 as a source is copied to storage device 93 as a destination, before the life of the storage device 92 is expired, whereby preserving the data continues, with migrations from one storage device to another across several generations (see Kohyo (National Publication of Translated Version) No. H10-508967, hereinafter referred to as “Patent Document 1”).
Furthermore, in order to preserve the valuable information in a form of electronic data without illegally modified, following measures are necessary. That is, a recording medium such as CD-R or DVD-R, which is available for write once only (Write-Once Media) may be utilized. Alternatively, as shown in FIG. 14B, computer 94 stores the electronic data in storage device 95 such as hard disk, and then, sets the storage area of the electronic data to write protect. Subsequently, the electronic data is made available for read only (For example, see Japanese Patent Laid-open Publication No. H3-3159, hereinafter referred to as “Patent Document 2”).